I love how Jesus references Jonah in the book of Matthew. Matthew 12:38-41 Jesus confirms that Jonah was in the belly of the great fish for three days and three nights. How far can a great fish travel in three days and three nights? The route suggested above is quite lengthy.
I have to admit when I saw where Nineveh was on a map I had to reconfigure the mental image I had in my mind from reading. However, that happens often as we read and then see a visual of the places and regions we are learning about. I'm completely comfortable with the possibility that wherever God had Jonah spit out, that he may have had to walk in obedience for some time to get to Nineveh, 3 days or more days. Many interpret the three days mentioned to be in relation to the size of Nineveh, the amount of time it would take to canvas the entire city with the message the Lord sent him to share.